Recently when I blogged about the SEO benefits of contributing to Wikipedia , I alluded to some of the complex strategies and tactics around creating entries, keeping your edits from getting reverted, etc.
One of the benefits that can no longer be gained is link juice. That’s because rel=nofollow has just been instituted across all of Wikipedia and its sister sites  (such as Wikinews).
Does that mean you no longer need to concern yourself with Wikipedia? Heck no! It is still a valuable source of traffic and, just as importantly, credibility. To have a Wikipedia entry for your company show up in the top 10 in Google for your company name gives a nice credibility boost. Even better if the coverage on your entry is favorable!
Wikipedia is still key to the discipline of “reputation management.” By understanding the ins and outs of Wikipedia — navigating the landmines of notability criteria, not contributing your company’s entry yourself, disambiguation pages, redirects, User pages, Talk pages, etc. — you can potentially influence what is said about you on Wikipedia. Furthermore, if web pages that are critical of your company occupy spots in the first page of the SERPs, you can push them out and replace them with your Wikipedia entries. Because Wikipedia holds so much authority and TrustRank, it’s easy to get an entry into the top 10 for any keyword.
Back to the nofollowing of external links… I don’t think SEOs will leave Wikipedia any time soon due to this new development. Even though that was Jimbo Wales’ hope.
There is still significant incentive for SEOs to edit (and manipulate) Wikipedia so long as Wikipedia holds the top spot for important keywords such as “marketing” in Google.